Ok after some other discussion that prodded me into this I decided to give it a try again.

That is, I calculated the pure loss with mp3 and mpc encoders in CoolEdit (Mix Paste, both channels inverted & Overlap) and listened the pure loss in each case with different quality settings. I observed that with mp3 standard preset, I can still figure out the melody because I can still hear some instruments (probably because of low pass filter). With MPC I hear the swoosh sound intensifying in some parts of the sample esp. when the original sample's volume is high. The average volume of the loss decreases as I increase the quality setting.

Could you tell me your points why this is not a good way of objectively evaluating how successful a lossy codec is? I think it's nice because the difference is not masked by the rest of the sample (which is usually higher in volume and dominates). But I can also imagine that using this way one cannot figure out stereo separation artifacts and even though when the pure loss is listened as a sample and sounds tolerable, the actual encoding result might have noticeable differences and is non-transparent. But isn't this also a reasonable method to supplement the results about which encoder is more successful? Can't we conclude anything objectively or subjectively by observing the pure loss? It sounds to me the discarded information is more tolerable a loss in q4 MPC than lame standard mp3 3.93.1.

This post has been edited by atici: Jul 12 2003, 20:51

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The object of mankind lies in its highest individuals.One must have chaos in oneself to be able to give birth to a dancing star.

(...) I observed that with mp3 standard preset, I can still figure out the melody because I can still hear some instruments (probably because of low pass filter). With MPC I hear the swoosh sound intensifying in some parts of the sample(...) It sounds to me the discarded information is more tolerable a loss in q4 MPC than lame standard mp3 3.93.1.

Just a question : have you decoded your mp3 first with LAME, in order to remove the additional samples ? If not, your test is biased : Fhg decoding engine will maintain the 'gap'.

I had fun some times ago with this tool. I find interesting to mesure the real loss of the encoding process. Nevertheless, you can't evaluate the quality of two encodings by this way. The stronger difference (= noise) isn't necessary the most ABXable file. I tried to oppose MPC and Vorbis by this way ; mpc seemed to be the most degraded one, but after a carefully blind listening test, I only heard a difference (hiss) for the vorbis file.

Note that this tool is interesting in order to detect artifacts similar to the erhu effect.